Fallow period for cryptocaryon irritans (ich)

[snorvich]

A normal distribution is a very important statistical data distribution pattern occurring in many natural phenomena, such as height, longevity of a member of a population e.g. human being.s For this discussion we are focused on the life cycle of Cryptocaryon irritans, otherwise known as marine ich. Certain data, when graphed as a histogram (data on the horizontal axis, amount of data on the vertical axis), creates a bell-shaped curve known as a normal curve, or normal distribution.

Normal distributions are symmetrical with a single central peak at the mean (average) of the data. The shape of the curve is described as bell-shaped with the graph falling off evenly on either side of the mean. Fifty percent of the distribution lies to the left of the mean and fifty percent lies to the right of the mean. The average life cycle of Cryptocaryon irritans is 3 weeks.

The spread of a normal distribution is controlled by the standard deviation. The smaller the standard deviation the more concentrated the data. Unfortunately, there is no published value for the standard deviation of the life cycle of Cryptocaryon irritans.

If you look at the percentages of population members within a standard deviation of the mean, we see that approximately 19.1% of normally distributed data is located between the mean (the peak) and 0.5 standard deviations to the right (or left) of the mean. For Cryptocaryon irritans, we are going to assume that 68% of the members lie within one standard deviation of the mean.

If you add percentages, you will see that approximately:
"¢ 68% of the distribution lies within one standard deviation of the mean.
"¢ 95% of the distribution lies within two standard deviations of the mean.
"¢ 99.7% of the distribution lies within three standard deviations of the mean.

These percentages are known as the "empirical rule". What this means for Cryptocaryon irritans is that leaving a tank fallow for 3 weeks will give you a 68% chance that you have eradicated the parasite, leaving a tank fallow for 6 weeks will give you a 95% chance of eradication, but if you want 99.7% chance, you will leave the tank fallow for 9 weeks. That is the reason you see different numbers being used on Reef Central and in the literature.

I see confusion when different numbers are used for the required fallow period to make sure you tank is ich free. Perhaps this will clarify. Or not!

 

[Akrite]

I would have to agree with this statement. I had my tank without fish for 2 months (8 weeks) and treated all my fish with Cupramine copper for 6 weeks and just under 2 months after returning them to my tank I saw the first sign of ich on my Achilles tang. It slowly spread to most of the fish shortly after. I'm starting to think the only way to fully get rid of ich is to start over with new water and go through a full cycle or wait 90 days with no fish in the display tank while treating your fish with copper or hypo for the recommended time.

 

[MrTuskfish]

Snorvich, valuable info! I'm sure you've heard rumors (IMO) of the new ''super strains" of C.I.; that are rumored to stay dormant for several months, or whatever the current rumor is saying. While I'm not a scientist, the common sense side of my brain says that the limited number of hobbyists, plus the constant influx of new fish (and CI), plus the number of CI that go without any attempt to eliminate them; would make mutation into a "super strain" of CI highly unlikely. Any thoughts? I always enjoy reading your well-researched material, thanks!

 

[snorvich]

Snorvich, valuable info! I'm sure you've heard rumors (IMO) of the new ''super strains" of C.I.; that are rumored to stay dormant for several months, or whatever the current rumor is saying. While I'm not a scientist, the common sense side of my brain says that the limited number of hobbyists, plus the constant influx of new fish (and CI), plus the number of CI that go without any attempt to eliminate them; would make mutation into a "super strain" of CI highly unlikely. Any thoughts? I always enjoy reading your well-researched material, thanks!

Interesting subject. I do believe that there are multiple strains of CI, perhaps some endemic to the Pacific and some endemic to the Caribbean. I do not think it likely that mutations will occur, BUT, our closed environments (compared to the ocean) make the probability higher. I am sure that for any population, there are members whose life expectancy is in the tail of the normal distribution. If those were isolated and their longevity was genetic rather than probabilistic, there could be a problem.

 

[Gogandantess]

I would have to agree with this statement. I had my tank without fish for 2 months (8 weeks) and treated all my fish with Cupramine copper for 6 weeks and just under 2 months after returning them to my tank I saw the first sign of ich on my Achilles tang. It slowly spread to most of the fish shortly after. I'm starting to think the only way to fully get rid of ich is to start over with new water and go through a full cycle or wait 90 days with no fish in the display tank while treating your fish with copper or hypo for the recommended time.

I'm totally frustrated by this disease. My display has been fallow for 2 months now. If ich happened to mysteriously appear again, I'm giving up and going back to African Cichilds.

 

[snorvich]

I'm totally frustrated by this disease. My display has been fallow for 2 months now. If ich happened to mysteriously appear again, I'm giving up and going back to African Cichilds.

Well this thread is not really oriented in that direction, but try quarantining.

 

[Fish4Me2]

Forgive me, as it's been a few years since grad school, but if I combine your statement about there being no published standard deviation for ich, with your statements about the normal curve, I can't predict when any percentage of ich will be gone. Heck, if I take a very depressing viewpoint, I haven't even seen any data to support that the ich lifecycle follows a normal curve. It could just as well be skewed, with fewer perishing before three weeks than after. Is there some part of the logic or research I'm missing here? My tank is currently fallow, so nine weeks sounds delightful, but I'd like to understand the info you are presenting better before moving livestock and risking contamination.

 

[jjk_reef00]

Great thread Steve, How long should you qt new rock, macro algae etc before adding it to your system? It sounds like 9-10 weeks.

 

[CanhMan]

Quick question, hopefully not a stupid one...
Can I turn off my skimmer during the fallow period?

 

[snorvich]

Quick question, hopefully not a stupid one...
Can I turn off my skimmer during the fallow period?

Sure. No issues whatsoever.

 

[cougaran]

You also have to be careful in NOT raising the temperature of the tank. While this is the correct method of controlling freshwater ich, it is not recommended for Saltwater ich. It has to do with the ich going into a protective cyst when the water temp is too high and there isnt any fish to complete the cycle. So leave the temp alone and let the ich follow its natural course. I also agree on a longer Hypo period than what most recommend only because it only takes one to reinfect all your fish... I also like to throw in a few dips for good measure to help insure of eradication.

 

[snorvich]

Actually freshwater dips will have no impact on cryptocaryon irritans since they embed much deeper than oodinium.

 

[Reefing Newbie]

So I should be waiting 9 weeks before adding my fish back into my tank or the 8 week fallow period? The two damsels that I am trying to catch got ich Got a hospital tank up for them.

 

[luamada]

Sos

Sos

I am desperate because my blue tang got some black spots on it today. What should I do.... help
I took a picture but I don't know how to put the picture in here...

 

[125mph]

So fallow period is 9 weeks for 99% success? Some say 12 weeks and some even say 16 weeks.. I had a tiny ich outbreak and promptly removed the fish within 2 days of the first white spot, so probably the waters aren't too infested.. 9 weeks should be enough?

 

[luamada]

ich cure

ich cure

a little update on my situation. First of all thank you all for this wonderful website. This is a true treasure in this marine world.
Well I started with ich after I had added a blemmie fish to my tank with the hope that he would stir the sand for me and I would not have to worry about that daily. BUT the nightmare started the next day. My blue tank who has been with me for about 4 years now, started with black ich. It took me two days to figure it out what he had. Thank God he was still eating. LFS suggested the medication "Kordon -ich attack ich treatment". I used almost a whole bottle and nothing, and fish was getting worse. Then they suggested to use "Dr. G's anti-parasitic Rx medicatated frozen banquet". I used for one week now (not sure if that is too long). I make sure that I cut it in sizes that the fish can eat since it is in blocks frozen. The following day the fish looked much better. Today, I can only see traces of the ich in my blue tang but he looks much better and I can tell that he is doing better too... Funny enough on the first few days of being sick, he would come so close to the glass and look into my eyes almost begging for help. It broke my heart to see him like that. Now he comes over and look at me and swim fast around as if to say thank you for feeling better. I know this sounds crazy but it is the truth. The first time when he got sick was the first time that he got so close to me in the fish tank and I could see in his eyes that he was really sick. POOR BABY. I am so happy now that he is so much better. I am not sure how long I should keep the treatment but I guess I will follow the empirical rule and go for the 99.7 ratio
thank you for all the help...
lu

 

[musarra]

I've found doing nothing id the best cure for black ick as its rarely fatal and only transmissible between certain fish. When my blue and yellow tangs broke out in regular ick i used a furan solution in a five gallon bucket for an hour then ten days in a copper solution then both fish went right back in the display and i've no problems for over a year.

 

[Parasitology]

FAO Snorvich

Although the use of statistical analysis to illustrate the maximum tomont excystment is useful. It hasn't taken into account the published data on C.irritans tomont release. #

Peak excystment at 25C takes place at 6 +/- 2 days.

Maximum tomont excystment time was 72 days at 25C. (Colorni)

 

[snorvich]

FAO Snorvich

Although the use of statistical analysis to illustrate the maximum tomont excystment is useful. It hasn't taken into account the published data on C.irritans tomont release. #

Peak excystment at 25C takes place at 6 +/- 2 days.

Maximum tomont excystment time was 72 days at 25C. (Colorni)

Actually, I did. Hence the 100 percent figure for 10 weeks of being fallow.

 

[aandfsoccr04]

bump for a very well written informative piece of information.